Method and apparatus to reduce radio resource overhead associated with intermittent traffic

ABSTRACT

A method and apparatus for No-TX mode for a wireless transmit/receive unit (WTRU) and Node B that suspends the transmission of power control updates and associated signaling over dedicated uplink and downlink channels. Triggers and signals between the WTRU and Node B to activate and disable No-TX mode. A radio link is re-established to resume data transmission when No-TX mode is disabled, and data may also be transmitted during defined transmission opportunities while in No-TX mode.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. provisional application No.60/955,579, filed Aug. 13, 2007, which is incorporated by reference asif fully set forth.

FIELD OF INVENTION

This application is related to wireless communications.

BACKGROUND

Power control is essential in mobile wideband code division multipleaccess (WCDMA) communications systems to mitigate the near-far problemand to keep the rise over thermal (RoT) noise below an acceptable level.The near-far problem occurs when multiple transmitters transmit fromdifferent distances to a receiver, such that signals received fromnearby transmitters cause greater interference and reduces thesignal-to-noise ratio (SNR) of signals received from more distanttransmitters. For example, this problem may arise when multiple wirelesstransmit/receive units (WTRUs) are communicating with a base station, orequivalently a Node B, in a wireless communications system.

Wireless communications systems based on code division multiple access(CDMA) technology, and in particular Third Generation PartnershipProject (3GPP) WCDMA frequency division duplex (FDD) systems, thereforerely on a closed-loop power control mechanism to improve systemperformance. In typical WCDMA systems, uplink (UL) power is adjustedusing regularly transmitted Transmission Power Control (TPC) commandsfrom a Node B carried on the downlink dedicated physical channel (DPCH),or the fractional DPCH (F-DPCH), to a wireless transmit/receive unit(WTRU). The downlink (DL) power is adjusted using TPC commands from theWTRU carried on the uplink dedicated physical control channel (DPCCH) tothe Node B. The uplink DPCCH also carries pilot bits in order to performchannel estimation at the receiver, such that the pilot bits enableaccurate demodulation of the received signal. FIG. 1 shows aconventional usage of power-control loop channels in a WCDMAcommunications system. The WTRU and the Node B are each equipped with atleast a processor, a transmitter and a receiver for use in transmittingand receiving communication signals over an established radio linkincluding the F-DPCH or DPCH and the DPCCH. The processor operatesaccording to a layered communications protocol, and generally includes amedium access control (MAC) layer component (layer 2), a physical (PHY)layer component (layer 1) and higher layer components (layer 3 andabove) including, but not limited to, a radio resource control (RRC)layer component and a radio link control (RLC) layer component.

Transmission of the DPCCH on the uplink represents a significant poweroverhead, which not only reduces the battery power at the WTRU but alsocreates additional noise rise at the Node B. In addition, thetransmission of the F-DPCH or DPCH on the downlink also contributes topower overhead and, even more importantly, consumes scarce CDMA coderesource. In general, maintaining the power control loop is relativelycostly and should be limited to when necessary, that is, when the WTRUtransmits or receives data.

The 3GPP WCDMA FDD standards specify a number of modes and states ofoperations for a mobile WTRU to allow efficient use of power and radioresources. The amount of resource and power used by a WTRU depends onits current mode and state. In general, a WTRU in IDLE mode carries outcell search and uses very little power. Once in connected mode, a WTRUcan be in one of four states: CELL_PCH state, URA_PCH state, CELL_FACHstate and CELL_DCH state. In CELL_PCH state and URA_PCH state, the WTRUmonitors the network for paging messages and communicates mobilitymessages to the network, and accordingly uses very small amounts ofpower and network resources. In CELL_FACH state, the WTRU continuouslymonitors the network for possible dedicated messages and thereforerequires more power and network resources. A WTRU in CELL_FACH state caninitiate data transmission on the random access channel (RACH), however,the RACH is only suitable for small amounts of data. In CELL_DCH state,all dedicated resources are allocated to the WTRU and the power controlloop is maintained continuously. This is the most power-intensive stateand it is designed for continuous transmission from and to the networkand for carrying larger amounts of data. Details on the relationshipsbetween the different states are described in 3GPP Technical Standard(TS) 25.331 V7.5.0, which is incorporated herein.

In 3GPP high speed downlink packet access (HSDPA) Release 7, a number offeatures were introduced to reduce power control overhead associatedwith the transmission of voice over internet protocol (VoIP) and othersporadic traffic. In particular, the Discontinuous Transmission (DTX)and Discontinuous Reception (DRX) modes of operation were provided toallow the WTRU and Node B to reduce the frequency of power control andchannel quality information (CQI) reporting, thereby increasing thenumber of users that can be supported in a cell. While these modes ofoperation are efficient for VoIP and similar types of traffic, DTX andDRX do not provide sufficient power-saving capabilities for trafficcharacterized by long periods of inactivity followed by short-lengthmessages or bursty traffic. Examples of this type of traffice includevirtual private network (VPN) keep-alive messages, uniform resourcelocator (URL) requests, internet browsing, file downloads and email. Inthese cases, during a long period of inactivity (also called a readingtime), the power control loop, that is DPCCH and F-DPCH/DPCH, is stillmaintained even if no data is transmitted.

For these types of data traffic, it becomes inefficient to maintain theresource-consuming power control loop in CELL_DCH state. The powercontrol overhead directly limits the number of users that can beserviced and translates into additional noise rise on the UL andadditional interference levels on the DL. It also leads to inefficientuse of the scarce battery resources of the WTRU. One option using thecurrent technology of 3GPP HSDPA Release 7 is to move a WTRU fromCELL_FACH state (or CELL_PCH state, Universal Terrestrial Radio AccessNetwork Registration Area Paging Channel (URA_PCH)) to CELL_DCH stateevery time a new message needs to be transmitted, and the WTRUsubsequently returns to CELL_FACH state (or CELL_PCH state, URA_PCH)state. However, this procedure would result in large signaling andresource overhead. In addition, maintaining the WTRU in CELL_FACH statewould not be appropriate as the legacy RACH is not designed to transmitlarge amounts of data.

Additionally, an important resource in the HSDPA network is the Node BDL code space. The DPCH enhancements in 3GPP HSDPA Release 6 and Release7 reduce the downlink power overhead associated with the Node B DL codespace but fail to reduce the code overhead as the F-DPCH code resourcesare also assigned to DRX receiving WTRUs. As a result, the F-DPCH coderesources cannot be used by other WTRUs.

Therefore, it is desirable to increase efficiency of the radio link byremoving dependence on the DPCCH continuous transmission between WTRUsand Node Bs. Techniques for efficient use of scarce battery resources byreducing radio overhead in long periods of inactivity, reducinginterference caused by control channels and increasing code availabilityon the DL, are also desirable.

SUMMARY

A method and apparatus to reduce radio resource overhead associated withintermittent traffic are disclosed. In particular, a No-TX mode ofoperation is defined where TPC commands are suspended on the dedicatedchannel. Triggers and signaling allow wireless transmit/receive units(WTRUs) and Node Bs to stop the transmission of power control updatesand associated signaling over the uplink dedicated physical controlchannel (DPCCH) and the downlink dedicated physical channel (DPCH) orfractional DPCH (F-DPCH) while remaining in a CELL_FACH state, oralternatively CELL_DCH state. As a result, system capacity and WTRUbattery life are increased while allowing the transmission of powercontrol updates and associated signaling to be resumed faster than ifthe WTRU would have entered CELL_DCH state. WTRUs maintain part of theirconfiguration in No-TX mode such that resuming transmissions do notrequire a state change. Therefore, there is a reduction in latency andsignaling overhead. In one embodiment, a set of downlink and uplinktransmission opportunities are defined by the network for communicationwhen No-TX mode is activated. In another embodiment, a set of resourcepersistence options are defined to describe the level by which radioresources and configuration parameters are released or maintained by theWTRU while in No-TX mode. In another embodiment, a set of triggers andmethods are provided by which No-TX mode can be activated. In anotherembodiment, a set of triggers and methods are provided by which theNo-TX mode of operation can be deactivated and dedicated channeltransmissions can resume for data transmissions. In another embodiment,a set of methods by which a WTRU can resume communication with the NodeB while being in No-TX mode are provided. In another embodiment, atechnique for radio link re-establishment following the deactivation ofNo-TX mode is provided in order for typical CELL_FACH or CELL_DCH radiotransmission operations to resume. In another embodiment, a method for aWTRU in No-TX mode to obtain radio resources or configuration withoutany explicit signaling from the Node B is provided. In anotherembodiment, temporary allocation of radio resources for those users inNo-TX mode is provided. In another embodiment, techniques for providingfast partial link reconfiguration messages to the WTRU are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1 shows a conventional usage of power-control loop channels in awideband code division multiple access (WCDMA) communications system;

FIG. 2 is a flow diagram for a ramp-up procedure for WTRU transmissionsin No-TX Mode; and

FIG. 3 shows a hashing function diagram using shared information todetermine a downlink dedicated physical channel code and offset indexwithin the code.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “wireless transmit/receiveunit (WTRU)” includes but is not limited to a user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a computer, or any othertype of user device capable of operating in a wireless environment. Whenreferred to hereafter, the terminology “base station” includes but isnot limited to a Node-B, a site controller, an access point (AP), or anyother type of interfacing device capable of operating in a wirelessenvironment.

A new mode of operation is provided during which Transmission PowerControl (TPC) commands are suspended. This new mode of operation isreferred to herein as No-TX (“no transmit”) mode for convenience;however, other names may be used as desired. More generally, No-TX modemay be interpreted as a new form of CELL_FACH state in the sense that nodedicated physical channel (DPCH) or fractional DPCH (F-DPCH) resourcesare assigned but provides reduced time to resume full transmission ofdata when needed. No-TX mode and the methods and embodiments providedherein may be applied to any wireless communications system incurringpower control overhead and employing power control loops. The teachingsherein are primarily described for wideband code division multipleaccess (WCDMA) communications systems with respect to a WTRU inCELL_FACH state for illustrative purposes, however, they may also beapplied to, for example, WTRUs in CELL_DCH state.

Downlink and Uplink Transmission Opportunities

According to a first embodiment, a set of downlink (DL) and uplink (UL)transmission opportunities are defined by the network for communicatingwhen No-TX mode is activated. When No-TX mode is activated, the DLF-DPCH or DPCH and UL dedicated physical control channel (DPCCH) are nolonger transmitted. In order to resume the transmission of the DL F-DPCHor DPCH and UL DPCCH, the network provides transmission opportunities toboth the Node B and the WTRU. These transmission opportunities take theform of a listening period at the receiving end, which is the WTRU onthe DL and the Node B on the uplink, respectively. For example, duringnetwork (Node B) transmission opportunities (or equivalently WTRUlistening periods), the WTRU listens for possible network transmissions.During WTRU transmission opportunities (or equivalently networklistening periods), the network (Node B) listens for possible WTRUtransmissions.

The transmission opportunities (or equivalently the listening periods)may be signaled by higher layers or may be pre-configured. Thetransmission opportunities may also take the form of known cyclicpatterns. Optionally, uplink and downlink transmission opportunitycyclic patterns may be defined independently for additional flexibility.Alternatively, the listening periods can be defined using the existingcontinuous packet connectivity (CPC) definitions but with longer cycles.

In No-TX mode, as the listening periods become long, it is possible forthe network to configure transmission opportunities so that there isminimum overlap between different WTRUs in the No-TX mode. This providesan opportunity for the network to multiplex resources including, forexample, high-speed shared control channel (HS-SCCH) codes, enhanceddedicated channel (E-DCH) hybrid automatic repeat request (HARQ)acknowledgement (ACK) indicator channel (E-HICH) codes or others.According to an alternate embodiment, the network may not provide WTRUtransmission opportunities and instead use polling during networktransmission opportunities.

Resource Persistence Options

According to another embodiment, a set of resource persistence optionsare provided describing the level by which radio resources andconfiguration parameters are released or maintained by the WTRU while inthe No-TX mode. In a conventional communication system, the Node B mayallocate various resources to WTRUs entering CELL_FACH state. Inparticular, the Node B may allocate a radio network temporary identifier(RNTI), uplink scrambling code, at least one frame offset, downlinkchannel codes, and signatures for the various control and data channelsto each WTRU in CELL_FACH. Some of these resources, such as the numberof downlink channelization codes and signatures, are limited.

When WTRUs enter No-TX modes, some of these resources may be released atthe system level so that the resources may be used by other WTRUs. Atleast one of several resource persistence options may be configured forNo-TX mode. The following resource persistence options may be used: fullpersistence; DL E-DCH control channel release; and DL control channelsrelease. In full persistence, a WTRU in No-TX mode keeps all theallocated resources and maintains its configuration. In DL E-DCH controlchannels release, a WTRU in No-TX mode releases all of the downlinkcontrol channel related to the enhanced dedicated channel (E-DCH)including, for example, the E-DCH relative grant channel (E-RGCH), E-DCHhybrid automatic repeat request (HARQ) acknowledgement indicator channel(E-HICH), and E-DCH absolute grant channel (E-AGCH), but keeps theF-DPCH (or DPCH) allocation and related offsets as well as their variousradio network temporary identifiers (RNTIs), uplink scrambling codes andother resources and configurations. In DL control channels release, aWTRU in No-TX mode releases all of the downlink control channelresources, including channelization codes, signatures, and frame offset,but keeps the various RNTIs, uplink scrambling codes and other resourcesand configurations.

A specific No-TX mode resource persistence option may be signaled to theWTRU from higher layers with the possible associated parameters ofoperations. Alternatively, the WTRU may be configured to use a specificresource persistence option and the parameters associated to that optionare signaled from higher layers or pre-defined.

In an alternative embodiment, the resource persistence option may changein time so that more information is released after longer periods ofinactivity. By way of example, the following resource persistence optionpattern may be configured or signaled. When initiating No-TX mode, thefull persistence option is enabled. After a specific time period ofinactivity (that may be pre-defined or signaled), for example in termsof a number of TTIs, frames or another duration measurement, thepersistence option changes automatically to downlink (DL) E-DCH controlchannels release. Then, after another specific time period ofinactivity, the persistence option changes automatically to DL controlchannels release. Other resource persistence patterns may also bedefined, as desired.

Enabling No-TX Mode

A set of triggers and methods may activate a No-TX mode. To enable atleast one No-TX mode with at least one WTRU, there exist severalpossible methods.

In one embodiment, a No-TX mode is enabled upon configuration of theradio link. The No-TX mode may be activated immediately uponconfiguration or after a time-delay that is either signaled orpre-configured.

In another embodiment, a No-TX mode is enabled through higher layersignaling, preferably with layer 3 acknowledgment (ACK). The start timeof at least one No-TX mode is signaled by higher layers, such as theradio resource control (RRC), as part of the message. Alternatively, theNo-TX modes start time is implicitly determined by the arrival time ofthe higher layer message, or the transmission time of the uplink (UL)acknowledgement (ACK).

In another embodiment, a No-TX mode is enabled after a specified periodof inactivity, where the actual value for the time period of inactivityused as triggering criteria can be signaled by higher layers orpre-defined. In one embodiment, a phased approach may be defined. Forexample, consider X, Y and Z to be numbers greater than 0. An inactivityperiod of duration X triggers the CPC DTX operation while a moreprolonged inactivity period of X+Y triggers the No-TX mode. If the WTRUis in a CELL_DCH state, a third phase may be included where an even moreprolonged period of X+Y+Z triggers the WTRU to transition to CELL_FACHstate.

In another embodiment, a No-TX mode is enabled when the WTRU sends arequest to the radio access network (RAN), or Node B, to start a No-TXoperation. An application on the WTRU, being in a privileged position tomonitor the battery levels and the traffic usage, may trigger thetransmission of a message requesting the RAN for No-TX mode to bestarted. Such a request may include No-TX mode parameters such as thestart time and proposed transmission opportunity patterns and/or cyclesfor the No-TX mode. In the preferred embodiment, the request to the RANand potential response from the RAN are preferably signaled by higherlayers.

In another embodiment, a No-TX mode is enabled using a high speed sharedcontrol channel (HS-SCCH) order, preferably with layer 1 ACK. Thecurrently reserved bit in the HS-SCCH order type field may be used toindicate the new type of order. This approach would leave 2 bits in theorder type field to indicate enabling or disabling of the No-TX mode,and can carry additional information. Alternatively, a new HS-SCCHformat can be defined for enabling No-TX mode. Further, in an alternateembodiment, new combinations of the channelization code set bits,modulation bit and/or transport block size can be specified for the newHS-SCCH order. This approach has the advantage that more bits areavailable which can be used to carry additional information. Then, thestart time and possibly other parameters related to the No-TX mode canbe implicitly determined by the relative timing of the HS-SCCH order orfrom the time of ACK.

Disabling No-TX Mode

A set of triggers and methods can deactivate the No-TX mode of operationin order to resume DPCCH transmissions. Upon disabling the No-TX mode,the WTRU returns to regular CELL_FACH state (or, alternatively, CELL-DCHstate) and may be configured to include DRX and/or DTX periods. Thisbehavior may be either signaled by higher layers, such as atconfiguration, or pre-configured.

In a timer-based method, both the WTRU and the Node B know the instantof time No-TX mode is disabled. This time instant can be specified by atime-delay relative to the enabling of the No-TX mode, or alternativelyit can be specified as an absolute time in terms of frame and subframenumber. The time instant can be signaled by higher layers duringconfiguration or the enabling of the No-TX mode, or pre-configured. Theresources required to re-establish the radio link can also be configuredby higher layers during configuration or the enabling of the No-TX mode,or pre-configured. Upon disabling of the No-TX mode, the Node B and WTRUcan re-establish the radio link. Techniques for re-establishing theradio link from No-TX mode are discussed in detail below.

In a network initiated method, the network initiates the disabling ofthe No-TX mode. In a first embodiment, the Node B polls the WTRU duringspecific network transmission opportunities or, equivalently, WTRUlistening periods. The polling message from the Node B may containresource allocation information to avoid the need for RRC or other typesof higher layer messaging for resource allocation. This feature isparticularly useful since only a few parameters need to be configured.The allocation may be signaled implicitly or explicitly or incombination. The actual information contained in the message depends onthe resource persistence option.

In the case of the full persistence option, no resource allocation isnecessary. For the DL E-DCH control channels release option, the E-HICHchannelization code, E-HICH and E-RGCH signatures and E-AGCHchannelization code and possibly others are signaled. In addition tothose resources, the F-DPCH or DPCH channelization code and offset, andpossibly other information, also need to be allocated and signaled inthe case of DL control channels release option.

The polling may be carried out using various approaches, including aHSDPA-like approach, a HS-SCCH-less like approach, a HS-SCCH orderapproach, a new channel approach, and a paging approach.

In the HSDPA-like approach, the WTRU already has a high-speed downlinkshared channel (HS-DSCH) Radio Network Transaction Identifier (H-RNTI)and a list of codes to listen to for the HS-SCCH. As part of the No-TXmode RRC configuration, the list of HS-SCCH codes to listen to may bereduced for WTRUs in No-TX mode. Then, the HS-SCCH and HS-DPCH may beused to transmit control data to the WTRU. Since there is no activeclose-loop power control in No-TX mode, to keep the transmission powerat a reasonable level the data portion of the transmission signal shoulduse strong coding and/or be transmitted with higher power. Theconfigurable number of HARQ retransmissions may also be used to addrobustness.

In the HS-SCCH-less like approach, the same approach as the HSDPA-likeapproach is used but no HS-SCCH transmission is performed. To reduce thedecoding complexity at the WTRU, a smaller number of channelizationcodes for listening and a limited number of transport formats may beconfigured or signaled to the WTRU. The HS-DPCH contains the resourceallocation, which may be used when the WTRU has data to transmit.

In the HS-SCCH order approach, a HS-SCCH order may also be used tosignal polling to the WTRU by using the existing reserved bit to createa new order type. Alternatively, new combinations of the channelizationcode set bits and modulation bit and/or transport block size can bespecified for the new HS-SCCH order. This approach has the advantagethat more bits are available which can be used to carry additionalinformation, such as channelization code allocation information.

In the new channel approach, a new channel can be defined for thepolling mechanism that may include some or all channel allocationrequired. For example, this channel can indicate a set of resources tobe used out of a collection of possible sets that has been previouslybroadcast or sent to the WTRU at association.

In the paging approach, a paging channel can additionally be used forpolling. After the polling message has been sent, the Node B listens forthe WTRU answer for a given period of time, which can be signaled byhigher layers or pre-configured.

In response to a polling message, the WTRU transmits an acknowledgmentif the WTRU has data in it's transmit buffer. The acknowledgementmessage may take one of the following forms. In a first form, theacknowledgment (ACK) message is in the form of a transmission of one orseveral UL DPCCH slots preferably using a ramp-up procedure. Thisramp-up procedure is described in further detail below. In another form,the ACK message is transmitted on the high-speed DPCCH (HS-DPCCH). Inaddition to the UL DPCCH, the WTRU may also transmit the HS-DPCCHacknowledgment to the Node B. The associated DPCCH transmission powercan be set using a ramp-up procedure, or by using an open-loop controlmechanism with additional power headroom, as signaled by higher layersor pre-configured. The HS-DPCCH power offset with respect to the DPCCHmay be signaled by higher layers or pre-configured. In addition, achannel quality indication (CQI) report and/or a scheduling request canbe sent at the same time, providing additional information to the NodeB. In another form, a new channel, which combines elements of the ULDPCCH and the HS-DPCCH, may be used to transmit an acknowledgement ifthe WTRU has data in the transmit buffer of the WTRU. This new channelmay use the procedure and concepts described below, and may containadditional information about the WTRU transmit buffer. For example, thenew channel may contain scheduling information, CQI, and otherinformation.

Based on the ACK received from the WTRU, the Node B is aware that theWTRU has data to transmit and begins a link re-establishment procedure,as described below.

When the WTRU has no data to transmit, provided WTRU transmissionopportunities exist, the WTRU may not answer the Node B poll.Alternatively, when the WTRU has no data to transmit, the WTRU mayinform the Node B that there is no data in the WTRU transmit buffer viaa negative acknowledgement (NACK). The WTRU may optionally providemeasurements to the network, and/or signal to the network that the WTRUis active and present. It may be advantageous for the WTRU to respond tothe Node B in the same way the WTRU communicates with the Node Bdescribed above. When there are no defined WTRU transmissionopportunities, the WTRU answers the Node B poll using the mechanismdescribed above.

If the Node B has data to transmit to a WTRU in No-TX mode, the Node Bmay use one of the network transmission opportunity defined for thatWTRU. The Node B sends an initial message to the WTRU during a networktransmission opportunity. For example, the Node B may use one of thesignaling methods described above. In particular, the initial Node Btransmission may or may not contain data and may contain channelconfiguration information for the WTRU. Then, the WTRU acknowledges theNode B by using one of the methods described above. Lastly, after theNode B has received the acknowledge message, a radio-link initializationprocedure is started and data transfer may begin.

Alternatively, during network transmission opportunities, the WTRU andthe Node B may re-establish the radio link. This can be achieved if theF-DPCH is allocated, as is the case when using the full persistenceoption, and by following the radio link re-establishment proceduredescribed below. However, the disadvantage of this method is that theradio-link is re-established at every network transmission opportunity,thereby wasting radio resources and battery power.

In another embodiment, the WTRU initiates the disablement of No-TX mode.If the WTRU has data to transmit, the WTRU waits for the next availableWTRU transmission opportunity. To inform the Node B of the state of theWTRU transmit buffer, the WTRU may send a request to the Node B by usingdifferent mechanisms described below. After successfully sending therequest, the Node B is aware that the WTRU has data to transmit andstarts a link re-establishment procedure. If the WTRU fails to seize thetransmission opportunity, such as when the WTRU does not receive a NodeB answer or acknowledgment for a given time period, then the WTRU mustwait for the next transmission opportunity to retry. Alternatively,after a given number of failed attempts, the WTRU may use the RACH tocontact the Node B using standard techniques. The network determines ifthe WTRU keeps its radio resources or may reconfigure the WTRU for newradio resources. Alternatively, if the WTRU is in a CELL_DCH state, theWTRU may autonomously revert to the CELL_FACH state and use the existingmechanism to request resources for data transmission.

WTRU Transmissions in No-TX Mode

Although the No-TX mode of operation is characterized by a suspension oftransmissions by the WTRU, there are occasions where a WTRU may need tosend transmissions to the Node B while in No-TX mode of operation. Theseoccasions may occur in, although not limited to, any of the followingexample situations. For example, there may be the need for the WTRU toleave the No-TX mode of operation and resume radio link synchronization(link re-establishment) with the Node B. There may be the need totransmit notifications, such as WTRU alive notifications, to the Node Bto indicate that the WTRU should still be considered as being active.This may imply that the WTRU should be kept in its current state,whether it be CELL_DCH state or CELL_FACH state. There may be the needto transmit measurements to the Node B, either scheduled or triggered,by an unpredictable mechanism such as a large variation of the measuredcommon pilot channel (CPICH) power. There may be the need to transmit anacknowledgment or answer to the Node B polling.

Four scenarios for WTRU transmissions while in No-TX mode are provided:(1) a ramp-up procedure allowing the WTRU to set its power in order tolimit undue noise rise increase at the Node B; (2) WTRU alivenotifications allowing a WTRU in No-TX mode to notify the Node B thatthe WTRU should still be considered as active; (3) channel acquisitiontransmissions to resume radio link synchronization; and (4) transmitpower control commands carried through high-speed shared control channel(HS-SCCH).

FIG. 2 is a flow diagram for a ramp-up procedure 200 for WTRUtransmissions in No-TX Mode. The No-TX mode permits a WTRU to stay inCELL_FACH state (or, alternatively CELL_DCH state) without any powercontrol loop for an extended period of time. In this period of time, thepath loss between the WTRU and the Node B may have varied greatly whichprevents a WTRU from simply resuming its transmissions using the lastpower setting it was using at the time it started the No-TX mode ofoperation. In order to limit undue noise rise increase at the Node Bfrom WTRU transmissions operating in No-TX mode, the WTRU uses thepower-ramping procedure 200 of FIG. 2.

In step 205, the WTRU calculates the power setting used to transmit theinitial burst. The power setting calculation may be based on one or moreof the following criteria: a pre-configured or signaled equationallowing the WTRU to derive a power setting from the above-describedelements; a power measurement from the CPICH; information signaled bythe Node B or pre-configured, including transmission power on the CPICHor different power settings and offsets on various downlink channels,whereby the WTRU estimates the CPICH power and the path loss between theNode B and the WTRU; and a margin, either signaled or pre-configured,that may be dependent on the noise rise measured by the Node B and isused by the WTRU to calculate the transmission power that should beused.

In step 210, the WTRU sends an initial transmission burst, which mayoptionally include an accompanying message. The initial burst canconsist of DPCCH transmission or a pre-defined or reserved sequencededicated to WTRU transmissions in No-TX mode. The accompanying messagecan include, but is not limited to: a radio resource request, forexample a F-DPCH request; a message indicating that the WTRU is stillactive, referred to as a WTRU alive notification; information abouttraffic buffered at the WTRU, such as a scheduling information (SI) orany other measurement taken by the WTRU; and small amounts of user datatraffic.

In step 215, the WTRU waits for a notification from the Node B thatacknowledges that it has received the transmission burst, which mayoptionally include an accompanying message. This notification from theNode B can be transmitted though the acquisition indicator channel(AICH), the E-HICH, the E-AGCH (with or without the associated grant),the HS-SCCH, the DPCH or F-DPCH or a new channel dedicated for thenotification. The accompanying message can include, but is not limitedto, a control message allocating radio resources and configuringparameters including channelization codes, time offsets, signatures forcontrol channels, or scheduling grants such E-AGCH.

In step 220, the WTRU determines if it has received the notificationwithin pre-determined period of time. If the WTRU receives notificationwithin the pre-determined period of time, the ramp-up procedure 200ends. If the WTRU does not receive the notification within thepre-defined period of time, the WTRU in step 225 transmits subsequentbursts at increments of increased transmission power until anotification from the Node B is received; after a pre-determined numberof failed transmission, the WTRU signals a failure to higher layers andthe ramp-up procedure 200 ends. In case of failure, and depending on theimportance of the transmission, the WTRU may optionally revert toexisting methods such as using the RACH for acquiring a channel tocommunicate with the Node B.

By definition, the No-TX mode suspends any signal from being transmittedfrom the WTRU to the Node B so the Node B can no longer rely on thepower control loop to monitor which users need to be kept in CELL_DCHstate, or and which users in CELL_DCH state need to be pushed toCELL_FACH or simply be disconnected. As mentioned above, one motivationfor a WTRU to transmit signals to the Node B while in No-TX mode is forthe Node B to be able to keep track of which WTRUs in No-TX mode shouldstill be considered as active, for which the Node B would continue toreserve some resources such as codes and/or memory, and which WTRUs needto be disconnected. Accordingly, the transmission burst and proceduredescribed above with respect to FIG. 2 may be used by the WTRU to notifythat it should still be considered as an active user. The WTRU alivenotification may be sent periodically, the period can be pre-configuredor signaled by the Node B, or it can be sent after being polled by theNode B.

One of the benefits of the No-TX mode is for the Node B to be able torelease and reuse some of the resources used by a WTRU that has nothingto transmit at a given instant. To that effect, different options interms of persistence of the radio resource allocation have beendescribed above. In order to leave the No-TX mode of operation, resumetransmitting data again and resume radio link synchronization with theNode B, the WTRU needs to get the radio resources that it had releasedwhen it entered the No-TX mode of operation. This may be performed bytransmitting a channel acquisition request to the Node B. The method andstructure underlying the channel acquisition request can be based on theprocedure defined above.

The radio resources or configuration parameters that the channelacquisition request may include: F-DPCH resources, for example frameoffset and channelization codes; E-AGCH resources, for examplechannelization codes; E-HICH and/or E-RGCH resources, for examplechannelization codes and signatures; and HS-SCCH resources, for examplechannelization codes. Alternatively, the resources can be allocatedbased on implicit rules as described below so that radio bandwidth maybe saved.

While in the No-TX mode the WTRU may be assigned an H-RNTI identifier toallow the serving cell to transmit power control commands to the WTRU inthe absence of an allocated F-DPCH. The assigned H-RNTI may be the sameas the one used in the normal CELL_FACH state, or alternatively normalCELL_DCH state. In one embodiment, the H-RNTI used is different from theone used in normal mode. This H-RNTI is called the secondary H-RNTI. Thesecondary H-RNTI may be shared and used to identify a single WTRU ormany WTRUs. Transmit power control commands may be sent at any of timeat the discretion of the network and are carried using a special format,type “P”, for the HS-SCCH. Such a format allows multiplexing of severalcommands destined to different WTRUs that share the same secondaryH-RNTI. In this case, the WTRU knows how to de-multiplex the bitscarrying its TPC commands from bits carrying commands from other WTRUsusing rules and pre-signaled allocations, such as a time slot. TheHS-SCCH type P may also be used to control the maximum data rate ofWTRUs instead of, or in addition to, the transmission power of theWTRUs. This would allow rate control in the absence of an allocatedE-RGCH.

Radio Link Re-Establishment

In the scenarios described above, the WTRU and Node B must re-establisha radio link when resuming operation from the No-TX mode. The radio-linkmay be considered re-established when the quality of the F-DPCH on thedownlink is acceptable and the transmission power levels are stabilizedby power control. To complete radio-link establishment, the F-DPCH codeand offset must be known by the WTRU and Node B.

In case the full persistence or DL E-DCH control channels releasepersistence options are used, or if the network has signaled the F-DPCHparameters explicitly or implicitly to the WTRU as part of the pollingmessage or the request answer, the WTRU knows which F-DPCHchannelization code and offset to use.

In the case of polling, the WTRU may start listening to the F-DPCH aftera given time period after transmitting its response message. In the caseof WTRU transmission opportunities, the WTRU may start listening to theF-DPCH after a given time period after transmitting the request or afterthe optional Node B answer, which may also contain a channel assignment.These time periods can be signaled by higher layers or configured.

In case the network makes extensive use of WTRU initiated transmission,a set of F-DPCH channelization codes and offsets can be shared amongseveral WTRUs with different WTRU transmission opportunities to avoidpossible collisions. This set may be signaled by higher layers orpre-configured. Optionally, the choice of which F-DPCH channelizationcode and offset used within the allowed set can be random or chosenaccording to pre-defined rules.

Alternatively, WTRUs sharing the set of F-DPCH channelization codes andoffsets may have overlapping transmission opportunities. The WTRUs mayselect the radio resources randomly or according to rules set so thatthere is little probability of collision, such as using information likethe H-RNTI and enhanced RNTI (E-RNTI). When there is a radio-linkre-establishment failure, the WTRU may try again at the next WTRUtransmission opportunity. When a number, signaled or pre-configured, offailed attempts has been reached, the WTRU reverts to CELL_FACH or otherpre-defined mechanism to contact the network.

The radio link re-establishment procedure may also depend on the timedelay from the last WTRU transmission. When the delay from the last WTRUtransmission is less than a given time period, referred to asT_LAST_UE_TX, which may be indicated by higher layers or configured, theradio-link should be considered “in-sync” and the existing procedurespecified in CPC should be used to re-start transmission. T_LAST_UE_TXshould be designed so that the probability of recovering the radio-linkusing the CPC procedure is large so that there is minimal impact onpower control. Typically, the value for T_LAST_UE_TX can be chosen to beless than or equal to the largest DTX time value allowed for CPC.Additional preamble slots may also be used to estimate the new powerlevel required to establish the radio link and to initialize powercontrol loop on both uplink and downlink. When the delay from the lastWTRU transmission is greater than T_LAST_UE_TX, the radio link should beconsidered broken and the existing radio link synchronizationinitialization procedure should be used.

In No-TX mode, as a result of measurements not being available for avery long period of time, existing radio link failure definitions maynot apply or apply only for a limited time after entering No-TX mode.After a defined link failure period of time has elapsed, the radio linkshould be considered lost and the radio-link initialization procedureshould be used.

Implicit Resource Allocation

As indicated above, the F-DPCH channelization code and offset must beknown by the WTRU to re-establish radio synchronization. In the DLcontrol channels release persistence option, this information is notavailable to the WTRU. The WTRU may be provided with this informationfrom the network via explicit signaling using one of the approachesdescribed above. Alternatively, the resource can be allocatedexplicitly. According to one embodiment, a mechanism for implicit F-DPCHcode and offset allocation for the WTRU is described.

The WTRU and the network share information that can be used to determinethe F-DPCH code and offset allocation. First, a set of F-DPCHchannelization codes and offsets are known by the network and WTRU asbeing available for selection. Typically, the network reserves a set ofchannelization codes and signals this information to the WTRU. The setof selectable channelization code can be optionally paired with specificoffsets, or alternatively the set of selectable channelization codes andthe set of offsets can be treated separately. Then, the network and WTRUdetermine the F-DPCH code and offset index within the at least one setspecified above based on a hashing function applied to a subset of theWTRU-specific information shared simultaneously by both the network andthe WTRU. FIG. 3 shows a hashing function diagram illustrating theshared information. The shared information provided to the hashingfunction may include a E-RNTI 302, a H-RNTI 304, a WTRU scrambling codeindex 306, and a timing of the WTRU's response 308, in number of slotsor TTIs, relative to the start of the listening period in the pollingcase or a timing of the Node B's response 308, in number of slots orTTIs, with respect to the transmission opportunity window in thetransmission opportunity case. The hashing function outputs the F-DPCHcode 310 and the F-DPCH code offset index 312. The hashing functionshould be designed to minimize the probability that two or more WTRUsare assigned the same resource.

Temporary Resource Allocation

Several WTRUs in No-TX mode may have different WTRU listening periodsand thus can share a temporary code resource, such as a F-DPCH code andcode offset. The temporary code resources can be signaled by higherlayers during configuration of the No-TX mode. Provided that no WTRUsare allocated the same code and listening period or pattern, there willbe no collision, as further described below. Once the radiosynchronization is re-established, the network can assign a newpermanent code allocation, possibly using a fast partial linkreconfiguration message. Alternatively, HS-SCCH-like orders can be usedto transmit power control commands temporarily before the F-DPCHchannelization code and offset are allocated.

Fast Partial Link Reconfiguration Message

A fast partial link reconfiguration message may be provided to the WTRU.According to one embodiment, fast partial link reconfiguration messagesare provided when a radio link is being re-established after an extendedperiod of no transmission, and some or all of the downlink controlresources need to be allocated. Fast partial link reconfigurationmessages may also be used where the resources were temporarily allocatedto the WTRU and need to be re-allocated.

The fast partial link reconfiguration message may contain one or more ofthe following configuration information: a F-DPCH channelization code; aF-DPCH frame offset; a E-HICH and E-RGCH channelization code; a E-HICHsignature; a E-RGCH signature; HS-SCCH channelization codes; and variousradio network temporary identities such as the E-RNTI, H-RNTI andothers. When the partial link reconfiguration message contains smallamount of data information, layer 1 (L1) messaging may be used. Forexample, a new HS-SCCH order with possibly additional payload on theHS-DPCH containing the new allocation may be used. Alternatively, a newRRC message containing the some or all of the information listed abovemay be used.

The techniques herein specify mechanisms to improve the number ofintermittently transmitting users that may be supported by a ThirdGeneration Partnership (3GPP) High Speed Downlink Packet Access (HSDPA)Release 7, and beyond, network. These methods and embodiments may alsobe applied to other wireless communication systems. The disclosedtechniques permit the WTRU and Node B to increase the efficiency of theradio link by removing the dependence on the DPCCH continuoustransmission. Advantages of the proposed techniques include: reducingradio overhead in long period of inactivity; increasing system capacityby reducing interference from the control channels and higher codeavailability on the DL; and improving battery performance in the WTRU bymore efficiently using scarce battery resources.

Although features and elements are described above in particularcombinations, each feature or element can be used alone without theother features and elements or in various combinations with or withoutother features and elements. The methods or flow charts provided hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable storage medium for execution by ageneral purpose computer or a processor. Examples of computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The WTRU may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth® module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) display unit,an organic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB)module.

1. A method for power control for wireless communications with reducedradio resource overhead where transmission power control (TPC) commandsare transmitted over shared dedicated channels comprising: suspendingTPC commands on the shared dedicated channel when a No-TX mode isenabled; and transmitting at least one message during a transmissionopportunity period to resume data transmission.
 2. The method of claim 1wherein the transmission opportunity period is signaled by higherlayers.
 3. The method of claim 1 wherein the transmission opportunityperiod is pre-configured.
 4. The method of claim 1 wherein thetransmission opportunity period forms a known cyclic pattern.
 5. Themethod of claim 1 further comprising: listening for possibletransmissions during a listening period.
 6. The method of claim 1 foruplink power control of a wireless transmit/receive unit (WTRU) whereinthe shared dedicated channel is a downlink dedicated physical channel(DPCH) or fractional DPCH (F-DPCH).
 7. The method of claim 6 wherein thetransmission opportunity period is such that there is minimum overlapwith transmission opportunity periods of other WTRUs.
 8. The method ofclaim 1 for downlink power control of a Node B wherein the shareddedicated channel is an uplink dedicated physical control channel(DPCCH).
 9. The method of claim 1 further comprising: when the no-TXmode is enabled, maintaining all allocated resources and configurations.10. The method of claim 1 for uplink power control further comprising:when the no-TX mode is enabled, releasing all downlink control channelsrelated to an enhanced dedicated channel and maintaining a fractionalDPCH (F-DPCH) allocation, related offsets, radio network temporaryidentifiers (RNTIs) and uplink scrambling codes.
 11. The method of claim1 further comprising: when the no-TX mode is enabled, releasing alldownlink control channel resources and maintaining network temporaryidentifiers (RNTIs).
 12. The method of claim 11 further comprisingmaintaining uplink scrambling codes.
 13. The method of claim 1 furthercomprising activating the No-TX mode upon configuration of a radio link.14. The method of claim 1 further comprising: receiving signaling fromhigher layers indicating activation of the No-TX mode; and activatingthe No-TX mode based on the signaling received from the higher layers.15. The method of claim 14 wherein the receiving signaling from higherlayers includes receiving a layer 3 acknowledgement.
 16. The method ofclaim 1 further comprising: receiving signaling in the form of a layer 1acknowledgment using a high speed shared control channel (HS-SCCH) orderindicating activation of the No-TX mode; and activating the No-TX modebased on the received signaling.
 17. The method of claim 1 furthercomprising activating the No-TX mode after a pre-determined period ofinactivity.
 18. The method of claim 17 further comprising receiving avalue for the pre-determined period of inactivity from higher layers.19. The method of claim 1 further comprising: activating a discontinuoustransmission (DTX) mode after a period of inactivity of duration X; andtransitioning to a No-TX mode after a period of inactivity of durationX+Y, where X and Y are numbers greater than
 0. 20. The method of claim 1performed by a wireless transmit/receive unit (WTRU) further comprising:sending a request to a radio access network (RAN) to enable the No-TXmode based on a trigger received from an application layer.
 21. Themethod of claim 20 wherein the sent request includes No-TX modeparameters including at least one of a start time and a proposedtransmission opportunity pattern or cycle.
 22. The method of claim 1further comprising: disabling the No-TX mode based on a set of triggers;re-establishing a radio link; and resuming transmission of TPC commandsover the shared dedicated channel.
 23. The method of claim 22 whereinthe disabling of No-TX mode is based on a pre-determined timeout periodthat is known at both a transmitter and a receiver.
 24. The method ofclaim 22 performed by a wireless transmit/receive unit (WTRU) whereinthe disabling the No-TX mode based on a set of triggers furthercomprises: while in No-TX mode, receiving polling messages from a Node Bduring pre-defined WTRU listening periods; and if the WTRU has data in atransmit buffer, transmitting an acknowledgement to the Node B tore-establish the radio-link with the Node B.
 25. The method of claim 24further comprising: if the WTRU has no data to transmit, ignoring thepolling messages received from the Node B.
 26. The method of claim 24further comprising: if the WTRU has no data to transmit, transmitting amessage to the Node B indicating that there is no date in the transmitbuffer.
 27. The method of claim 24 wherein the polling messages furtherinclude resource allocation information.
 28. The method of claim 27wherein the resource allocation information includes at least one of anenhanced dedicated channel (E-DCH) hybrid automatic repeat request(HARQ) acknowledgement indicator channel (E-HICH) channelization code,E-HICH signature, E-DCH relative grant channel (E-RGCH) signature andE-DCH absolute grant channel (E-AGCH) channelization code.
 29. Themethod of claim 28 wherein the resource allocation information furtherincludes at least one of downlink dedicated physical channel (DPCH) orfractional DPCH (F-DPCH) channelization code and offset.
 30. The methodof claim 22 performed by a Node B wherein the disabling the No-TX modebased on a set of triggers further comprises: transmitting an initialmessage to a mobile station during the transmission opportunity period;receiving an acknowledgement from the mobile station; andre-establishing a radio link with the mobile station for data transfer.31. The method of claim 30 wherein the initial message includes at leastone of data and channel configuration information for the mobilestation.
 32. The method of claim 22 performed by a wirelesstransmit/receive unit (WTRU) wherein the disabling the No-TX mode basedon a set of triggers further comprises: receiving an initial messagefrom a Node B during a listening period; transmitting an acknowledgmentto the WTRU; and re-establishing a radio link with the Node B for datatransfer.
 33. The method of claim 22 performed by a wirelesstransmit/receive unit (WTRU) wherein the disabling the No-TX mode basedon a set of triggers further comprises: if the WTRU has data totransmit, transmitting a request to a Node B to disable No-TX modeduring the transmission opportunity period; and re-establishing theradio link with the Node B if a confirmation message is received fromthe Node B, otherwise re-transmitting the request during a nexttransmission opportunity period.
 34. The method of claim 33 furthercomprising: sending a message to the Node B over a random access channel(RACH) after a number of re-transmission attempts have exceeded athreshold.
 35. The method of claim 22 performed by a Node B wherein thedisabling the No-TX mode based on a set of triggers further comprises:receiving a request from a mobile station to disable No-TX mode during alistening period; transmitting a confirmation message to the mobilestation; and re-establishing the radio link with the mobile station. 36.The method of claim 1 performed by a WTRU that has data to transmitwhile No-TX mode is enabled further comprising: calculating a powersetting for transmitting a transmission burst; transmitting thetransmission burst, wherein the transmission burst may optionallyinclude an accompanying message; waiting to receive a notification froma Node B that acknowledges that it has received the transmission burst;and if the WTRU does not receive the notification within a pre-definedperiod of time, transmitting subsequent transmission bursts atincrements of increased transmission power until a notification from theNode B is received, wherein the WTRU signals a failure to higher layersafter a pre-determined number of transmission bursts have beentransmitted without receiving the notification from the Node B.
 37. Themethod of claim 36 wherein the transmission burst includes at least oneof a dedicated physical control channel (DPCCH) transmission and apre-defined or reserved sequence dedicated to WTRU transmissions inNo-TX mode.
 38. The method of claim 36 wherein the accompanying messageincludes at least one of: a radio resource request, a message indicatingthat the WTRU is still active, information about traffic buffered at theWTRU, scheduling information (SI), measurements taken by the WTRU, andsmall amounts of user data traffic.
 39. The method of claim 36 whereinthe calculating the power setting is based on at least one of thefollowing: an equation based on the accompanying message, a powermeasurement from a common pilot channel (CPICH), information signaledfrom a Node B, a transmission power on the CPICH enabling estimation ofa path loss between the Node B and the WTRU, power settings of downlinkchannels, offsets of downlink channels, and a margin based on a noiserise measured by the Node B.
 40. The method of claim 36 wherein thenotification from the Node B further includes an accompanying message.41. The method of claim 40 wherein the accompanying message with thenotification from the Node B is a control message for allocating radioresources and configuring parameters including at least one ofchannelization codes, time offsets, signatures for control channels, andscheduling grants.
 42. The method of claim 36 wherein the notificationfrom the Node B is received over at least one of: an acquisitionindicator channel (AICH), an enhanced dedicated channel (E-DCH) hybridautomatic repeat request (HARQ) acknowledgement indicator channel(E-HICH), an E-DCH absolute grant channel (E-AGCH), a high-speed sharedcontrol channel (HS-SCCH), a dedicated physical channel (DPCH) orfractional DPCH (F-DPCH) or a new channel dedicated for thenotification.
 43. The method of claim 36 wherein the transmitting atransmission burst is transmitted periodically and the transmissionburst serves as a WTRU alive notification.
 44. The method of claim 1performed by a wireless transmit/receive unit (WTRU) further comprising:transmitting a channel acquisition request to a Node B to request radioresources that it released when entering a No-TX mode.
 45. The method ofclaim 44 wherein the requested radio resources include at least one of:fractional dedicated physical channel (F-DPCH) resources including frameoffset and channelization codes; enhanced dedicated physical channel(E-DCH) absolute grant channel (E-AGCH) resources includingchannelization codes; enhanced dedicated channel (E-DCH) hybridautomatic repeat request (HARQ) acknowledgement indicator channel(E-HICH) and/or E-DCH relative grant channel (E-RGCH) resourcesincluding channelization codes and signatures; and high-speed sharedcontrol channel (HS-SCCH) resources including channelization codes. 46.The method of claim 1 performed by a wireless transmit/receive unit(WTRU) wherein the WTRU is assigned a high-speed downlink shared channel(HS-DSCH) Radio Network Transaction Identifier (H-RNTI) furthercomprising: receiving TPC commands from a Node B while No-Tx is enabled,wherein the TPC commands are received using a special format forhigh-speed shared control channel (HS-SCCH).
 47. The method of claim 1further comprising: re-establishing a radio link when No-TX mode isdisabled.
 48. The method of claim 47 wherein: the re-establishing theradio link is based on a known shared dedicated channel channelizationcode and offset.
 49. The method of claim 47 performed by a wirelesstransmit/receive unit (WTRU) wherein the re-establishing the radio linkfurther comprises: listening to the shared dedicated channel after apre-determined period of time.
 50. The method of claim 47 performed by awireless transmit/receive unit (WTRU) wherein the re-establishing theradio link further comprises using a set of shared dedicated channelchannelization codes and offsets to re-establish the radio link.
 51. Themethod of claim 50 wherein the set of shared dedicated channelchannelization codes is signaled by higher layers.
 52. The method ofclaim 50 wherein the set of shared dedicated channel channelizationcodes is accessed randomly.
 53. The method of claim 50 wherein the setof shared dedicated channel channelization codes is selected based oninformation to reduce a probability of collision on the shared dedicatedchannel channelization codes.
 54. The method of claim 50 furthercomprising: if the radio-link re-establishment fails, attempting tore-establish the radio link at a next transmission opportunity.
 55. Themethod of claim 47 wherein the re-establishing the radio link depends ona time delay from a last transmission, wherein if the time delay is lessthan a T_LAST_UE_TX period, the radio link is ready for datatransmission.
 56. The method of claim 47 further comprising determiningresource allocation based on a hashing function applied to a subset ofwireless transmit/receive unit (WTRU) shared information that is sharedsimultaneously by the WTRU and a Node B.
 57. The method of claim 56wherein the shared information includes at least one of: an enhancedradio network temporary identifier (E-RNTI); a high-speed radio networktemporary identifier (H-RNTI); a WTRU scrambling code index; a timing ofthe WTRU's response in number of slots or transmission time intervals(TTIs); and a timing of the Node B's response in number of slots orTTIs.
 58. A wireless transmit/receive unit (WTRU) configured to conductpower control for wireless communications with reduced radio resourceoverhead where transmission power control (TPC) commands are transmittedover shared dedicated channels comprising: a transmitter configured tosuspend TPC commands on the shared dedicated channel when a No-TX modeis enabled; and the transmitter configured to transmit at least onemessage during a transmission opportunity period to resume datatransmission.
 59. The WTRU of claim 58 configured as a mobile station.60. The WTRU of claim 58 configured as a Node B.
 61. The WTRU of claim58 configured as a Universal Mobile Telecommunications System (UMTS)Terrestrial Radio Access Network (UTRAN).
 62. The WTRU of claim 58wherein the transmission opportunity period is signaled by higherlayers.
 63. The WTRU of claim 58 wherein the transmission opportunityperiod is pre-configured.
 64. The WTRU of claim 58 wherein thetransmission opportunity period forms a known cyclic pattern.
 65. TheWTRU of claim 58 wherein: the transmitter is configured to listen forpossible transmissions during a listening period.
 66. The WTRU of claim58 configured to perform uplink power control wherein the shareddedicated channel is a downlink dedicated physical channel (DPCH) orfractional DPCH (F-DPCH).
 67. The WTRU of claim 66 wherein thetransmission opportunity period is such that there is minimum overlapwith transmission opportunity periods of other WTRUs.
 68. The WTRU ofclaim 58 configured as a Node B performing downlink power controlwherein the shared dedicated channel is an uplink dedicated physicalcontrol channel (DPCCH).
 69. The WTRU of claim 58 further comprising: aprocessor configured to maintain all allocated resources andconfigurations when the no-TX mode is enabled.
 70. The WTRU of claim 58for uplink power control further comprising: a processor configured torelease all downlink control channels related to an enhanced dedicatedchannel and maintain a fractional DPCH (F-DPCH) allocation, relatedoffsets, radio network temporary identifiers (RNTIs) and uplinkscrambling codes when the no-TX mode is enabled.
 71. The WTRU of claim58 further comprising: a processor configured to release all downlinkcontrol channel resources and maintaining network temporary identifiers(RNTIs) when the no-TX mode is enabled.
 72. The WTRU of claim 71 whereinthe processor is configured to maintain uplink scrambling codes.
 73. TheWTRU of claim 58 further comprising: a processor configured to activatethe No-TX mode upon configuration of a radio link.
 74. The WTRU of claim58 further comprising: a processor comprising: a medium access control(MAC) layer component configured to receive signaling from higher layercomponents indicating activation of the No-TX mode; and the processorconfigured to activate the No-TX mode based on the signaling receivedfrom the higher layers.
 75. The WTRU of claim 74 wherein the mediumaccess control (MAC) layer component is configured to receive signalingfrom higher layer components including a layer 3 acknowledgement. 76.The WTRU of claim 58 further comprising: a processor comprising: amedium access control (MAC) layer component configured to receivesignaling in the form of a layer 1 acknowledgment using a high speedshared control channel (HS-SCCH) order indicating activation of theNo-TX mode; and the processor configured to activate the No-TX modebased on the received signaling.
 77. The WTRU of claim 58 furthercomprising: a processor comprising: a medium access control (MAC) layercomponent configured to activate the No-TX mode after a pre-determinedperiod of inactivity.
 78. The WTRU of claim 77 wherein the MAC layercomponent is configured to receive a value for the pre-determined periodof inactivity from higher layers.
 79. The WTRU of claim 58 furthercomprising: a processor configured to activate a discontinuoustransmission (DTX) mode after a period of inactivity of duration X; andthe processor configured to transition to a No-TX mode after a period ofinactivity of duration X+Y, where X and Y are numbers greater than 0.80. The WTRU of claim 58 wherein: the transmitter is configured to senda request to a radio access network (RAN) to enable the No-TX mode basedon a trigger received from an application layer.
 81. The WTRU of claim80 wherein the transmitter is configured to include in the sent requestNo-TX mode parameters including at least one of a start time and aproposed transmission opportunity pattern or cycle.
 82. The WTRU ofclaim 58 further comprising: a processor configured to disable the No-TXmode based on a set of triggers; the WTRU configured to re-establish aradio link; and the transmitter configured to resume transmission of TPCcommands over the shared dedicated channel.
 83. The WTRU of claim 82wherein the processor is configured to disable the No-TX mode based on apre-determined timeout period that is known at the WTRU and at areceiving Node B.
 84. The WTRU of claim 82 wherein the processor isconfigured to disable the No-TX mode based on a set of triggers furthercomprising: a receiver configured to receive polling messages from aNode B during pre-defined WTRU listening periods while in No-TX mode; atransmit buffer configured to store data; and the transmitter configuredto transmit an acknowledgement to the Node B to re-establish theradio-link with the Node B if the transmit buffer has stored data. 85.The WTRU of claim 84 further comprising: the processor configured toignore the polling messages received from the Node B if the transmitbuffer is empty.
 86. The WTRU of claim 84 further comprising: thetransmitter configured to transmit a message to the Node B indicatingthat there is no date in the transmit buffer if the transmit buffer isempty.
 87. The WTRU of claim 84 wherein the receiver is configured toreceive polling messages that include resource allocation information.88. The WTRU of claim 87 wherein the resource allocation informationincludes at least one of an enhanced dedicated channel (E-DCH) hybridautomatic repeat request (HARQ) acknowledgement indicator channel(E-HICH) channelization code, E-HICH signature, E-DCH relative grantchannel (E-RGCH) signature and E-DCH absolute grant channel (E-AGCH)channelization code.
 89. The WTRU of claim 88 wherein the resourceallocation information further includes at least one of downlinkdedicated physical channel (DPCH) or fractional DPCH (F-DPCH)channelization code and offset.
 90. The WTRU of claim 82 configured as aNode B wherein the processor is configured to disable the No-TX modebased on a set of triggers wherein: the transmitter is configured totransmit an initial message to a mobile station during the transmissionopportunity period, further comprising: a receiver configured to receivean acknowledgement from the mobile station; and the Node B configured tore-establishing a radio link with the mobile station for data transfer.91. The WTRU of claim 90 wherein the transmitter is configured totransmit an initial message that includes at least one of data andchannel configuration information for the mobile station.
 92. The WTRUof claim 82 wherein the processor is configured to disable the No-TXmode based on a set of triggers further comprising: a receiverconfigured to receive an initial message from a Node B during alistening period; the transmitter configured to transmit anacknowledgment to the WTRU; and the WTRU configured to re-establishing aradio link with the Node B for data transfer.
 93. The WTRU of claim 82wherein the processor is configured to disable the No-TX mode based on aset of triggers further comprising: a transmit buffer configured tostore data; the transmitter is configured to transmit a request to aNode B to disable No-TX mode during the transmission opportunity periodif the transmit buffer has stored data; and the WTRU is configured tore-establish the radio link with the Node B if a confirmation message isreceived from the Node B, otherwise the transmitter is configuredre-transmit the request during a next transmission opportunity period.94. The WTRU of claim 93 wherein: the transmitter is configured to senda message to the Node B over a random access channel (RACH) after anumber of re-transmission attempts have exceeded a threshold.
 95. TheWTRU of claim 82 configured as a Node B wherein the processor isconfigured to disable the No-TX mode based on a set of triggers furthercomprising: a receiver configured to receive a request from a mobilestation to disable No-TX mode during a listening period; the transmitteris configured to transmit a confirmation message to the mobile station;and the Node B is configured to re-establish the radio link with themobile station.
 96. The WTRU of claim 58 wherein the WTRU has data totransmit while No-TX mode is enabled further comprising: a processorconfigured to calculate a power setting for transmitting a transmissionburst; the transmitter configured to transmit the transmission burst,wherein the transmission burst may optionally include an accompanyingmessage; a receiver configured to wait to receive a notification from aNode B that acknowledges that it has received the transmission burst;and if the receiver does not receive the notification within apre-defined period of time, the transmitter is configured to transmitsubsequent transmission bursts at increments of increased transmissionpower until a notification from the Node B is received, wherein theprocessor comprises a medium access control (MAC) layer configured tosignal a failure to higher layers after a pre-determined number oftransmission bursts have been transmitted without receiving thenotification from the Node B.
 97. The WTRU of claim 96 wherein thetransmitter is configured to transmit subsequent transmission burststhat include at least one of a dedicated physical control channel(DPCCH) transmission and a pre-defined or reserved sequence dedicated toWTRU transmissions in No-TX mode.
 98. The WTRU of claim 96 wherein thetransmitter is configured to transmit the transmission burst with theaccompanying message that includes at least one of: a radio resourcerequest, a message indicating that the WTRU is still active, informationabout traffic buffered at the WTRU, scheduling information (SI),measurements taken by the WTRU, and small amounts of user data traffic.99. The WTRU of claim 96 wherein the processor is configured tocalculate the power setting based on at least one of the following: anequation based on the accompanying message, a power measurement from acommon pilot channel (CPICH), information signaled from a Node B, atransmission power on the CPICH enabling estimation of a path lossbetween the Node B and the WTRU, power settings of downlink channels,offsets of downlink channels, and a margin based on a noise risemeasured by the Node B.
 100. The WTRU of claim 96 wherein the receiveris configured to receive a notification from the Node B that includes anaccompanying message.
 101. The WTRU of claim 100 wherein the receiver isconfigured to receive a notification from the Node B with theaccompanying message that is a control message for allocating radioresources and configuring parameters including at least one ofchannelization codes, time offsets, signatures for control channels, andscheduling grants.
 102. The WTRU of claim 96 wherein the receiver isconfigured to receive the notification from the Node B over at least oneof: an acquisition indicator channel (AICH), an enhanced dedicatedchannel (E-DCH) hybrid automatic repeat request (HARQ) acknowledgementindicator channel (E-HICH), an E-DCH absolute grant channel (E-AGCH), ahigh-speed shared control channel (HS-SCCH), a dedicated physicalchannel (DPCH) or fractional DPCH (F-DPCH) or a new channel dedicatedfor the notification.
 103. The WTRU of claim 96 wherein the transmitteris configured to transmit a transmission burst periodically and thetransmission burst serves as a WTRU alive notification.
 104. The WTRU ofclaim 58 further comprising: the transmitter configured to transmit achannel acquisition request to a Node B to request radio resources thatit released when entering a No-TX mode.
 105. The WTRU of claim 104wherein the requested radio resources include at least one of:fractional dedicated physical channel (F-DPCH) resources including frameoffset and channelization codes; enhanced dedicated physical channel(E-DCH) absolute grant channel (E-AGCH) resources includingchannelization codes; enhanced dedicated channel (E-DCH) hybridautomatic repeat request (HARQ) acknowledgement indicator channel(E-HICH) and/or E-DCH relative grant channel (E-RGCH) resourcesincluding channelization codes and signatures; and high-speed sharedcontrol channel (HS-SCCH) resources including channelization codes. 106.The WTRU of claim 58 wherein the WTRU is assigned a high-speed downlinkshared channel (HS-DSCH) Radio Network Transaction Identifier (H-RNTI)further comprising: a receiver configured to receive TPC commands from aNode B while No-Tx is enabled, wherein the TPC commands are receivedusing a special format for high-speed shared control channel (HS-SCCH).107. The WTRU of claim 58 wherein: the WTRU is configured tore-establish a radio link when No-TX mode is disabled.
 108. The WTRU ofclaim 107 wherein: the WTRU is configured to re-establish the radio linkbased on a known shared dedicated channel channelization code andoffset.
 109. The WTRU of claim 107 further comprising: a receiverconfigured to listen to the shared dedicated channel after apre-determined period of time.
 110. The WTRU of claim 107 wherein theWTRU is configured to use a set of shared dedicated channelchannelization codes and offsets to re-establish the radio link. 111.The WTRU of claim 110 further comprising: a processor comprising: amedium access control (MAC) layer component configured to receivesignaling from higher layers indicating the set of shared dedicatedchannel channelization codes.
 112. The WTRU of claim 110 wherein theWTRU is configured to randomly access the set of shared dedicatedchannel channelization codes.
 113. The WTRU of claim 110 wherein theWTRU is configured to select the set of shared dedicated channelchannelization codes based on information to reduce a probability ofcollision on the shared dedicated channel channelization codes.
 114. TheWTRU of claim 110 wherein: if the radio-link re-establishment fails, theWTRU is configured to attempt to re-establish the radio link at a nexttransmission opportunity.
 115. The WTRU of claim 107 wherein the WTRU isconfigured to re-establish the radio link depending on a time delay froma last transmission, wherein if the time delay is less than aT_LAST_UE_TX period, the radio link is ready for data transmission. 116.The WTRU of claim 107 wherein the WTRU is configured to determineresource allocation based on a hashing function applied to a subset ofWTRU shared information that is shared simultaneously by the WTRU and aNode B.
 117. The WTRU of claim 116 wherein the shared informationincludes at least one of: an enhanced radio network temporary identifier(E-RNTI); a high-speed radio network temporary identifier (H-RNTI); aWTRU scrambling code index; a timing of the WTRU's response in number ofslots or transmission time intervals (TTIs); and a timing of the NodeB's response in number of slots or TTIs.